Seiren

Seiren (セイレーン) is a 2 generation, Underwater Warfare Angeloid type η (Eta) (水中戦闘用エンジェロイドタイプη（イータ)) built by the Master of Synapse.

Appearance
She strongly resembles the mermaids of legend with her fin. Seiren's hands also resemble fins. Her wings float around her.

Plot
Seiren was impaled in the back by one of Chaos's wings before being devoured, and absorbed by her just after she was ordered by the Master of Synapse to kill Tomoki Sakurai and Ikaros.

Chaos uses her Pandora system to absorb her powers and escape from the Ocean.

Master of Synapse

 * The Man of Synapse is her master and creator.
 * Tomoki Sakurai- One of her assassination target.
 * Ikaros- enemy. However, they never meet.
 * Chaos-enemy. Chaos absorbs her to take her powers.

Trivia

 * Seiren's appearance is based on the Seiren of Greek mythology.
 * Even though an Angeloid's weakness is water, Seiren is able to work underwater.
 * Seiren can be in the Ocean up to 8000 meters deep.